The Internet Crime Complaint Center (IC3), a task force that includes the Federal Bureau of Investigation (FBI), on Wednesday issued a phishing warning to US telecom customers. Victims are seeing their accounts being taken over after attempting to login to malicious sites.

The IC3 says criminals are contacting individuals using automated telephone calls that claim to be from the victim’s telecommunication carrier. The messages then trick victims into visiting a site, a replica of one of the telecommunication carrier’s sites, where they think they will receive a credit, discount, or prize ranging from $300 to $500.

Instead, their accounts are being taken over, according to numerous reports of phishing attacks targeting “various telecommunication companies’ customers.” The IC3 says the criminals then make changes to the hijacked accounts, but wouldn’t elaborate what these might be.

The phishing site requests the victims’ login credentials and the last four digits of their Social Security numbers, often used as verification when accessing an account. Once victims enter their information, they are redirected to the telecommunication carrier’s actual website to reduce suspicion.

The organization offered the following advice:

The IC3 urges the public to be cautious of unsolicited telephone calls, e-mails and text messages, especially those promising some type of compensation for supplying account information. If you receive such an offer, verify it with the business associated with your account before supplying any information. Use the information supplied on your account statement to contact the business.

Although carriers were not mentioned by name, it’s fair to say that multiple companies were targeted, and most likely the more popular ones as they have the biggest potential to result in successful phishes. Remember: if you are contacted by someone out of the blue eager to give you money, whether it’s by phone, email, or text message, just ignore them.